1. Field of the Invention
The present invention relates to a hoseless driving tool in which compressed air of a pressure that is higher than the working pressure of an output section is stored in an air tank coupled to the tool body, and the high pressure compressed air in the air tank is supplied to the output section with reducing the pressure by a pressure reducing valve, to operate the output section, thereby driving a fastener such as a nail.
2. Description of the Related Art
The assignee of the present invention has proposed in Japanese patent application No. HEI11-73400 (U.S. Ser. No. 09/527,303) a hoseless driving tool in which an air tank for storing compressed air at a pressure that is higher than a pressure at which an output section is operable is attached to the body of the driving tool, and the high pressure compressed air in the air tank is supplied to an output section with reducing the pressure to operate the output section, thereby driving a fastener.
As compared with a conventional driving tool which is operated by supplying compressed air from an external compressed air source via an air hose or the like, the proposed hoseless driving tool has an advantage that the workability is excellent because the use of the tool is enabled without dragging an air hose and is not restricted by the place where an external compressed air source is disposed.
However, the attachment of the air tank, a pressure reducing valve, and the like causes the dimensions and the weight of the tool to be increased. In order to store compressed air at a pressure that is higher than the air pressure at which the output section is operable, particularly, the air tank must have a shell which is thicker than the output section. Depending on the arrangement of the air tank and the pressure reducing valve, therefore, the tool may difficult to use in a confined place, or the weight balance of the whole tool may be impaired. As a result the workability is sometimes lowered.
As shown in FIG. 1, for example, a pressure reducing valve 104 and a long air tank 103 may be arranged in series with starting from the rear end of a handle section 102, and on a line extended from the axis 170 of the handle section 102. In this case, the total length is so long that the tool is hardly used in a confined place. Since the air tank 103 which is heavy is remote from a gripping portion of the handle section 102, the center of gravity 140 of the whole driving tool is positioned behind the handle section 102. When the handle section 102 is gripped to hold the body, the moment acting on the hand is Mxe2x80xa2L where M is the weight of the tool body and L is the distance between the center 131 of the gripping portion 130 and the center of gravity 140. In the case of FIG. 1, the distance L is long, and therefore a large moment of gravity acts on the hand to impair the weight balance of the whole body, thereby producing problems such as that a large force is required for holding the driving tool in the direction to the target.
FIG. 2 is a front view of an example in which the air tank 103 is attached to another position. A plane 120 includes the axis 160 of an output section 101 and the axis 170 of the handle section 102. The air tank 103 has a shape in which the left side in the figure with respect of the plane 120 is larger. The air tank 103 causes the center of gravity 140 of the whole driving tool to be shifted from the plane 120 to the left side in the figure. According to this configuration, when the handle section 102 is gripped and the body is lifted by gripping the handle section 102, the body turns about the axis 170 of the handle section 102 so that the center of gravity 140 is positioned vertically below the handle section 102. Therefore, a nose 107 located above the axis 160 of the output section is directed obliquely downward, and hence it is difficult to aim the nose 107 at the driving position (FIG. 3). During a driving operation, a reaction 190 occurs in the direction toward the axis 160 of the output section, and the body tries to turn about the center of gravity 140. As shown in FIG. 4, when the center of gravity is positioned to be separated from the plane 120, rotation about the axis 170 of the handle section 102 is caused so that the body is tilted. As a result, a fastener 108 is driven while being bent, or a driver blade 109 is disengaged from the fastener 108 to strike a material to be fastened 150, so that the member 150 is easily damaged.
FIG. 5 shows a driving tool which has been proposed by the assignee of the present invention in Japanese Patent application No. HEI11-73400 (U.S. Pat. No. 6,220,496). In the driving tool, a piston 8 which is disposed in a cylinder 4 to be vertically moveable is driven by compressed air in a first accumulator chamber 2 disposed in the tool body 1, so that a fastener 6 is driven by a drive bit 7. A second accumulator chamber 20 is disposed which can store compressed air at a pressure that is higher than a pressure at which the tool body 1 is operable. The driving tool comprises: an air intake 16 which is connectable with an air compressor via an air hose or the like; a communication control valve 22 which controls communication between the second accumulator chamber 20 and the air intake 16; and a pressure reducing valve 21 through which the compressed air in the second accumulator chamber 20 is supplied to the first accumulator chamber 2 while reducing the pressure of the compressed air. The driving tool can be used without being connected with an air compressor via an air hose or the like. Consequently, the driving tool has features that the driving tool is free from cumbersome handling of an air hose and hence has excellent workability, and that the filling of compressed air can be easily performed. Also a configuration in which a discharge value through which, after the driving tool is used, the compressed air in the second accumulator chamber 20 is discharged is disclosed.
FIG. 6 shows a driving tool which has been proposed by the assignee in JP-A-10-109280. In the driving tool, an air duster mechanism is incorporated into the driving tool, so that a cleaning work of blowing wood chips and the like by the air duster and a driving operation by the driving tool are performed by one tool. The driving tool is used in a state where an air hose is connected with the driving tool, and therefore cannot be used without connecting an air hose.
Since compressed air is accumulated in the tool body as described above, the driving tool of FIG. 5 is preferably structured so that, after a driving work is ended, the compressed air in the tool body can be easily discharged to the atmosphere, and also that, after the driving work, a discharge valve can be operated as far as possible to completely discharge the compressed air from the tool body.
The driving tool shown in FIG. 6 incorporates the air duster mechanism, and therefore is very convenient for use. However, the driving tool cannot be used without connecting an air hose, and is restricted by the length of the air hose and the place where a compressed air source is disposed. Therefore, the driving tool has a disadvantage that the workability is poor. In the cleaning work by the air duster, particularly, the tool must be used with directing a nozzle to various directions in accordance with cleaning places, and hence it is cumbersome to handle the air hose.
Also, the above-mentioned driving tool shown in FIG. 5 is driven by the compressed air accumulated in the second accumulator chamber 20. Therefore, the driving tool can be used without being connected with an air compressor via an air hose or the like. Consequently, the driving tool has features that the driving tool is free from cumbersome handling of an air hose. When the driving operation is repeatedly performed, the compressed air in the second accumulator chamber 20 is consumed, and the pressure of the chamber is lowered. When the pressure is lower than the minimum pressure at which the tool body 1 can be driven, a driving failure such as that a fastener cannot be completely driven occurs, and finally the tool body 1 cannot be operated. When the driving tool is to be continuously used, therefore, it is required to refill the second accumulator chamber 20 with compressed air before the pressure of the second accumulator chamber 20 becomes lower than the minimum pressure at which the tool body 1 can be driven. In order to know the degree at which compressed air is accumulated in the second accumulator chamber 20, however, it is required to actually perform a driving operation and then judge whether the driving operation has been correctly performed or not. After the driving tool is used, it is preferable to discharge all compressed air in the second accumulator chamber 20 so as to make the chamber empty. In order to check whether the second accumulator chamber 20 is empty or not, it is required to perform a driving operation.
The invention has been made to solve the above problems with the prior art, and therefore an object of the present invention is to improve the arrangement of an output section, a handle section, and an air tank so as to reduce the dimensions, and to improve the weight balance so as to attain an enhanced workability.
Another object of the invention is to provide a driving tool which can eliminate the disadvantages of the driving tool having a second accumulator chamber, and that having an air duster, which can be simply configured, and which can be easily operated.
Still another object of the invention to provide a driving tool in which, even when a driving operation is not performed, the amount of compressed air in a second accumulator chamber can be easily known, so that a driving failure due to an insufficient pressure of the second accumulator chamber can be prevented from occurring and it is possible to easily check whether the second accumulator chamber is empty or not.
The above one object is attained by disposing an air tank behind a handle section, so that the center of gravity of the whole of a driving tool is positioned in the vicinity of a gripping portion of the handle section.
The one object is attained also by positioning an air tank and a pressure reducing valve so that, with respect to two regions which are separated from each other by a plane including axes of a handle section and an output section, a moment of gravity of a member(s) which is on a side of the axis of the handle section is substantially equal to a moment of gravity of a member(s) which is on another side of the axis, whereby a center of gravity of a whole of a driving tool is positioned in a vicinity of the plane.
The above another object is attained by a driving tool comprising: a first accumulator chamber which is disposed in a tool body; a second accumulator chamber in which compressed air can be accumulated, a pressure of the compressed air being higher than a pressure at which the tool body is operable; an air intake which is connectable with an air compressor via an air hose or the like; a communication control valve which controls communication between the second accumulator chamber and the air intake; and a pressure reducing valve through which the compressed air in the second accumulator chamber is supplied to the first accumulator chamber with reducing the pressure of the compressed air, a piston which is disposed in a cylinder to be vertically movable being driven by the compressed air in the first accumulator chamber, a fastener being driven by a drive bit attached to the piston, wherein a nozzle having an opening through which the compressed air is to be discharged, an air passage through which the nozzle communicates with the first accumulator chamber or the second accumulator chamber, and a discharge valve which controls discharging of the compressed air from the nozzle are operably disposed.
The above still another object is attained by providing a second accumulator chamber with a pressure gauge which measures the pressure of the second accumulator chamber.